Grate bar

ABSTRACT

A grate bar for combustion systems, having a substantially closed surface facing the combustion side, a rear support region designed to be placed on a grate carrier for forming the grate, and a front nose region, which is rounded between the surface and front edge and has a bearing surface designed on the lower face and further has cooling fins for air cooling which protrude from the lower face of the surface forming the grate. A head part in the interior has at least regionally thickened head fins for air cooling in the longitudinal direction and vertical direction below the surface facing the combustion side. The grate bar can also be a reversible grate bar.

The present invention pertains to a grate bar according to theintroductory clause of claim 1.

For the combustion of various fuels such as household trash, industrialwaste, wood chips, solid or porous fuels, and fuels which are easy toignite and those which are difficult, the conventional practice is touse incinerators with combustion chambers, in which the fuel is placedon, for example, a mechanically actuated grate, on which it is burned.

As a rule, the material processed in incinerators includes fuel withhigh heating value and fuel with low heating value, with the result thatsignificant heat-related problems can occur in regard to the grateelements. Especially in the head area of the grate elements, theelements can burn or corrode because of the high thermal load.

A goal of the present invention is to provide a grate bar whichcomprises a long service life.

The goal of the invention is achieved by means of a grate bar accordingto the text of claim 1. Additional embodiments are described in thedependent claims.

What is proposed is a grate bar for incinerators with

-   -   an essentially closed surface on the combustion side;    -   a rear support area, designed to be placed on a grate carrier to        form the grate;    -   a rounded nose at the front, between the surface and the leading        edge, with a support surface on the bottom side; and    -   cooling ribs for air cooling, which project from the bottom side        of the surface forming the grate,        wherein the interior of the head comprises head ribs in the        longitudinal and vertical directions, at least certain parts of        which are made thicker than the other parts, for air cooling the        combustion-side surface. As a result, the service life of the        inventive grate bar is significantly prolonged, because, after        exposure to heat has led to the erosion of the nose as a result        of, for example, chlorine corrosion among other processes, and        even though the head ribs may be blocked by combustion slag, the        thickened parts of the head ribs form an additional barrier        against the heat-caused loss of material and simultaneously        allow the head part to be cooled by the head ribs.

In another embodiment, the head ribs comprise two or more, preferablytwo, three, or four, thickened parts arranged parallel to each other. Inthis way the service life of the grate bar can be extended even longer,because, after the loss of the outermost combustion surface, at leastone more surface is available for heat-caused erosion.

In another inventive embodiment, the head ribs comprise essentiallytrapezoidal and/or funnel-shaped and/or polygonal and/or wedge-shapedthickened parts. It is conceivable that, if desired, the thickened partsof the head ribs could be exclusively polygonal or any desiredcombination of polygonal with other forms.

In another inventive embodiment, head slots are formed between a sidewall and each of the head ribs. As a result of the design of the headpart with head ribs and the head slots between them, the heat resultingfrom the combustion process can be dissipated across a large coolingsurface. The head slots make it possible for the combustion air tocirculate. The thermal wear occurs at first primarily on the head partof the grate bar. Once the combustion surface of the head part has beenlost by heat-caused wear, the area behind it, in the form of thethickened trapezoidal parts of the head slots which have been blocked bycombustion slag, are available for further wear. Thanks to the headslots, the combustion air can circulate and the head part can be cooled.

According to another embodiment, the head slots . . . a funnel, which isarranged inside the head part, the funnel leading to a tapered part ofthe head slot. The head ribs are arranged here between a lateral endwall and the extension-like head ribs, all of which together form acomb-like structure. According to yet another embodiment, approximatelythe forward third of the head ribs is thickened.

According to yet another embodiment, at least one part of the side wallcomprises a recess extending along the head part.

According to yet another embodiment, the grate bar comprises a rearpart, which is provided with a with at least one long slot, which isopen to the surface in the rear area, and wherein the cooling ribsproject into the interior of the rear part.

According to yet another embodiment, the grate bar is made of metal.

In an additional embodiment, the grate bar is designed as a reversiblegrate bar, with a rear nose designed in the same way as the front noseand head part. These types of reversible grate bars can be reversed whenthe first head part has reached the end of its life, and thus the otherhead part allows the grate bar to be used over an additional period oftime equivalent in practice to the service life of the first head part.For this purpose, two support surfaces are formed on the bottom side,arranged symmetrically with respect to the center of the grate bar.

Another aspect of the invention pertains to a grate for use in thegrate-firing chamber of an incinerator, wherein at least one transverserow of inventive grate bars is arranged in the grate in movable fashion,and wherein, following this first transverse row, a second transverserow with a grate bar an inventive grate bar is installed in stationaryfashion. This achieves the goal that the material to be burned can bemoved continuously toward the combustion side.

In another embodiment, the support surface of one grate bar overlaps thesurface of the following grate bar in an offset, fish-scale like manner.

In another embodiment, several grate bars are arranged with their longsides parallel to each other.

Exemplary embodiments of the present invention are explained in greaterdetail below on the basis of the figures:

FIG. 1 shows a schematic cross-sectional side view of an inventive gratebar;

FIG. 2 shows a schematic view similar to that of FIG. 1;

FIG. 3 shows a first enlarged cross section along line E-E in FIG. 2;

FIG. 4 shows a second enlarged cross section along line B-B in FIG. 2;

FIG. 5 shows a third enlarged cross section along line A-A- in FIG. 2;

FIG. 6 shows an enlarged head part of an inventive grate bar similar tothat of FIG. 7;

FIG. 7 shows a schematic plan view of an inventive grate bar;

FIG. 8 a shows a schematic cross-sectional side view of an another headpart of an inventive grate bar;

FIG. 8 b shows a schematic plan view according to FIG. 8 a;

FIG. 9 a shows a schematic cross-sectional side view of yet another headpart of an inventive grate bar;

FIG. 9 b shows a schematic plan view according to FIG. 9 a;

FIG. 10 a shows a schematic cross-sectional side view of yet anotherhead part of an inventive grate bar; and

FIG. 10 b shows a schematic plan view according to FIG. 10 a.

FIG. 1 shows a schematic cross-sectional side view C-C in FIG. 7 of aninventive grate bar 1 for an incinerator. These grate bars or elementscan be arranged horizontally next to each other to any desired width. Itis conceivable for the grate bars to be arranged in a first transverserow, with their long sides parallel to each other, after which at leastone additional transverse row follows the first row. The firsttransverse row can comprise stationary grate bars, whereas the gratebars of the other transverse row are movable. Moving the grate barsmakes it possible to transport the combustible material continuouslytoward the combustion side. It is conceivable that the transverse rowscould alternate; that is, a stationary row could be followed by amovable row, which is followed in turn by a stationary row, etc. Otherarrangements of stationary and movable transverse rows are alsoconceivable, however; for example, a movable transverse row could befollowed by two stationary rows, followed in turn by a movabletransverse row. One end 2 of the grate bar 1 is designed as a supportarea 2 with a nose-like shape, so that it can be attached to a bracketin an incinerator in the manner known in itself. The front end of thegrate bar 1 comprises a rounded edge or nose 3 with a leading edge 3′ asan extension of the top combustion surface 4. A surface 4′ underneaththe combustion surface 4 in the interior of the grate bar 1 can formanother combustion surface after the combustion surface 4 has been lostby heat-caused corrosion. The support area 2 and the nose 3 are designedin such a way that the grate bars 1 can overlap each other in fish-scalefashion; that is, the support surface 5 located under the nose 3 issupported by or rests on the surface or top combustion surface 4 of thefollowing grate bar 1, the set of such bars thus forming the gratesurface of the incinerator. The grate bar also comprises a transverserib 6 and a rear part 7. An area 8 between the leading edge 3′ of thenose 3 and the transverse rib 6 forms the head part 8.

FIG. 2 shows a schematic view according to FIG. 1. The reference numbersalready introduced in FIG. 1 correspond to the features of FIG. 1. Alsoshown in FIG. 2 are a side wall 9 with recesses 10, 10′, 10″ andassembly openings 11 to allow the individual grate bars to be connectedto each other.

FIG. 3 shows a first enlarged cross section, in this case along line E-Ein FIG. 2. The combustion surface 4 at the top has a closed shape andmerges with a lateral end wall 12. Head ribs 13, 13′ are formed in afirst area A1 underneath the combustion surface 4 or, expresseddifferently, they are designed as extensions formed on the bottom sideof the combustion surface and projecting into the interior of the gratebar 1. The head ribs 13 extend in the longitudinal direction of thegrate bar 1 and also extend in the vertical direction. Head slots 14,14′ are formed between the head ribs 13, 13′. The head slots 14, 14′form grooves between the head ribs 13, 13′. The central head slot 14′comprises a funnel 15′, which is somewhat wider than the funnels 15 ofthe head slots 14 adjacent to it on either side. The head slots 14, 14′are open at the bottom. The head slots 14, 14′ are arranged between thelateral end wall 12 and the head ribs 13, 13′, designed as extensions ofthe head part 8, and form a comb-like structure in the interior of thehead part 8. The funnels 15, 15′ lead to a tapered part 16, 16′ of thecorresponding head slots 14, 14′.

FIG. 4 is a second enlarged cross section, this time along the line B-Bin FIG. 2. In the rear part 7, cooling ribs 17 of different sizesproject into the interior of the grate bar 1. Between the cooling ribs17 are gaps 18. The side wall 9 with the corresponding recess 10″ isalso shown.

FIG. 5 shows a third enlarged cross section, this time along the lineA-A in FIG. 2. The side wall 9 is interrupted by the assembly opening11. The cooling ribs 17 with the gaps 18 between them are also shown,the ribs proceeding from the combustion surface 4 and extending into theinterior of the grate bar 1.

FIG. 6 shows the enlarged head part 8 of the inventive grate bar in across section through area Z in FIG. 7. A second area A2 of thecombustion surface 4 is formed without head ribs 13, 13′ and without theintermediate head slots 14, 14′; that is, the second area A2 forms asolid one-piece sub-part of the head part 8. Following the second areaA2 is a third area A3 with the trapezoidal head ribs 13, 13′ and theintermediate head slots 14, 14′. The head ribs 13, 13′ and head slots14, 14′ extend toward the transverse rib 6 and proceed both in thelongitudinal and in the vertical direction of the head part 8. The headslots 14, 14′, which extend to an external side of the head part 8, areformed between the lateral end walls 12 and the associated head ribs 13.Following the second area A2 there is in each case a funnel-shaped inlet19, 19′ in the corresponding head slot 14, 14′. Each head slot 14, 14′comprises the tapered part 16, 16′, which leads to a funnel-shapedoutlet 20, 20′. The outlet 20, 20′ leads to a head slot part 21, 21′,which is wider than the tapered part 16, 16′. As a result, a part 22,22′ of the head ribs 13, 13′ has a thickened, essentially trapezoidalregion.

FIG. 7 shows a plan view of the inventive grate bar 1. The head part 8with the head slots 14, 14′ and the head ribs 13, 13′ and the rear part7 with the cooling ribs 17 and the intermediate gaps 18 are shown. Thehead slots 14, 14′ and the gaps 18 are arranged in series in thelongitudinal direction of the grate bar 1 and are connected to eachother. In the case of air-cooled grate bars, the temperature during thecombustion process is the highest in the head part 8, and thus theheat-caused wear is also the greatest here. As a result of the largecooling surface provided by the comb-like structure of the head ribs 13,13′ and as a result of the circulation of the combustion air through thehead slots 14, 14′, the heat can be effectively dissipated. After thesecond area A2 (see FIG. 6) has been eroded by thermal wear, thefollowing third area A3 (see FIG. 6) with the head ribs 14, 14′ isavailable for further thermal wear. The wear continues until thethickened trapezoidal parts 22, 22′ of the head ribs 14, 14′ have alsobeen lost as a result of heat.

FIG. 8 a shows a schematic cross-sectional side view of another headpart 8′ of an inventive grate bar. Here a first layer 23 to be carriedaway by heat corrosion is shown, which is formed at least in part by thecombustion surface 4. In addition, we also see in FIG. 8 a a secondlayer 24 and a third layer 25. The second layer 24 and the third layer25 are formed by the thickened head ribs 13, 13′. Between the firstlayer 23 and the second layer 24, there is a first recess 26. A secondrecess 27 lies between the second layer 24 and the third layer 25. Thesecond layer 24 follows in the direction toward the interior of theadditional head part 8′, coming after the first layer 23. The thirdlayer 25 follows the second layer 24 in the direction toward theinterior of the additional head part 8′. Following the third layer 25,the central head slot 14′ is shown. By means of these three layers 23,24, 25, which are designed to be eroded by heat corrosion, it ispossible for the inventive grate bar to have a longer service life, inthat, as a result of the heat-caused loss of the first layer 23, thereare still two more layers 24, 25 available for further loss, that is,for loss by thermal wear.

FIG. 8 b shows a schematic plan view according to FIG. 8 a. Here thethree layers 23, 24, 25 are shown. The second and third layers 24, 25comprise thickened polygonal parts 28, 28′, 29, 29′ on the head ribs 13,13′. The thickened polygonal parts 28, 28′, 29, 29′ project from theircorresponding head ribs 13, 13′ into the interior of the additional headpart 8′. The first layer 23 is followed by the first recess 26; thefirst recess 26 is followed by the second layer 24. The second layer 24is followed in turn by the second recess 27, which is followed by thethird layer 25. The slot 14′ proceeds from the third layer 25. Thecentral thickened parts 28′, 29′ are approximately twice as thick as thethickened parts 28, 29 extending on either side.

Between the thickened polygonal parts 28, 28′, 29, 29′ there lies ineach case an associated head slot 14, 14′.

FIG. 9 a shows a schematic cross-sectional side view of yet another headpart 8″ of an inventive grate bar. Here the three layers 23, 24, 25 areshown along with the recesses 26, 27.

FIG. 9 b shows a schematic plan view according to FIG. 9 a. In contrastto FIG. 8 a, the second layer 24 comprises thickened funnel-shaped areas30, 30′, and the third layer 25 comprises thickened polygonal areas 31,31′.

FIG. 10 a shows a schematic cross-sectional side view of yet anotherhead part 8″′ of an inventive grate bar. Three layers 23, 24, 25 areshown here. In addition, a fourth layer 32, which follows the thirdlayer 25, extends toward the interior of the additional head part 8″′.Between the third layer 25 and the fourth layer 32 there is anotherrecess 33.

FIG. 10 b shows a schematic plan view according to FIG. 10 a. Incontrast to FIGS. 8 a, and 9 a, the second layer 24 comprises thickenedwedge-shaped parts 34, 34′ and the third layer 25 comprises thickenedpolygonal areas 35, 35′. Following the third layer 25, the fourth layer32 with thickened polygonal parts 36, 36′ is also shown. This gives theinventive grate bar an especially long service life.

It is conceivable that the thickened parts of the head ribs 13, 13′described on the basis of the preceding figures could be combined witheach other in any desired way.

Features with the same reference numbers in FIGS. 1-10 b designate thesame technical features in the various figures.

1-13. (canceled)
 14. A grate bar for incinerators, comprising: asubstantially closed surface on a combustion side; a rear support areaconfigured to be placeable on a grate carrier to form the grate; a frontwith a rounded nose between the closed surface and a leading edge, andwith a bottom side having a support surface; cooling ribs for aircooling arranged to project from a bottom side of the closed surfaceforming the grate; and a head part that comprises head ribs for aircooling that extend in longitudinal and vertical directions of the gratebar underneath the combustion-side surface, at least certain parts ofthe head ribs being thicker than other parts of the head ribs.
 15. Thegrate bar according to claim 14, wherein the head ribs comprise at leasttwo thickened parts arranged parallel to each other.
 16. The grate baraccording to claim 14, wherein the head ribs comprise substantiallytrapezoidal and/or funnel-shaped and/or polygonal and/or wedge-shapedthickened parts
 17. The grate bar according to claim 14, wherein headslots are formed between a side wall and each of the head ribs.
 18. Thegrate bar according to claim 14, wherein the head slots form a funnel,which is arranged inside the head part, and the funnel leads to atapered part of the head slot, and wherein the head slots are arrangedbetween a lateral end wall and the extension-like head ribs, all ofwhich together from a comb-like structure.
 19. The grate bar accordingto claim 14, wherein a forward third of the head ribs is thickened. 20.The grate bar according to claim 17, wherein at least part of the sidewall extending along the head part comprises a recess.
 21. The grate baraccording to claim 14, further comprising a rear part provided with atleast one long slot open toward the closed surface, and wherein thecooling ribs project into an interior of the rear part.
 22. The gratebar according to claim 14, wherein the grate bar is made of metal. 23.The grate bar according to claim 14, wherein the grate bar is areversible grate bar, with a rear nose and head part configured the sameas the front nose and head part.
 24. A grate for use in a grate-firingchamber of an incinerator, comprising: a first transverse row; and asecond transverse row following the first transverse row, each of saidfirst and said second transverse rows having a grate bar according toclaim 14, the grate bar in said first transverse row being arranged inthe grate in movable fashion, and, the grate bar in said secondtransverse row being installed in stationary fashion.
 25. The grateaccording to claim 24, wherein the support surface of the grate baroverlaps the surface of a following grate bar in an offset, fishscale-like fashion.
 26. The grate according to claim 24, wherein severalgrate bars are arranged longitudinally parallel to each other in eachrow.